The present invention relates to the field of data transmission systems for downhole environments, such as along a drill string used in oil and gas exploration or along casings or other equipment used in oil and gas production. More particularly, this invention relates to a removable transmission network for transmitting and receiving data between downhole tools without requiring separate manufacture or substantial modification of any tool.
For most of the last century, the drilling industry has desired a means to communicate with sensors and other equipment located at the drill bit and along the drill string to facilitate efficient deep well exploration and excavation. As exploration and drilling technology has improved, this goal has become more important in the industry for successful oil, gas and geothermal well exploration and production. For example, to take advantage of the several advances in the design of various tools and techniques for oil and gas exploration, it would be beneficial to have real time data such as temperature, pressure, inclination, salinity, etc. Several attempts have been made to devise a successful system for accessing such drill string data; as of yet, however, the goal has been. unrealized.
One of the obstacles to realizing the goal of real time communication along a drill string is the wide variety of tools required for drilling a modern day well that a downhole transmission network must accommodate. Although at first glance many downhole tools seem to resemble one another, the industry thus far has been unable to develop a transmission network capable of accommodating variations between tools without compromising their structural integrity or requiring their special manufacture. This problem is exacerbated by certain downhole tools that require unique internal components to achieve unique functions related to drill exploration and excavation. Jars, motors, hammers, steering subs, and blow-out preventers, for example, each require special function internal components to achieve their specific purposes. A downhole transmission network capable of universal application to existing downhole tools must thus be able to accommodate both external and internal variances between tools without disrupting their unique functions or compromising their structural integrity.
The present invention recognizes that despite the variances between individual downhole tools designed to perform individual functions, all tools require a central passageway to permit the flow of drilling fluid from the surface to the drill bit and back again. The present invention seeks to exploit this passageway as a means by which to produce a downhole transmission network capable of universal application to preexisting downhole tools that are not configured to convey signals along their lengths (as described above) and neither disrupts the tools' unique functions nor compromises their structural integrity.